1. Field
The described technology generally relates to secondary batteries.
2. The Description of the Related Technology
In general, a secondary (rechargeable) battery includes i) an electrode assembly in a cylindrical shape, ii) a can coupled to the electrode assembly, iii) an electrolyte injected into the inside of the can to allow lithium ions to move, and iv) a cap assembly coupled to one side of the can, preventing a leakage of the electrolyte, and preventing a removal of the electrode assembly. Such a secondary battery usually has a capacity from about 2000 mA to about 4000 mA, and thus the secondary battery is mainly mounted in portable devices such as a notebook computer, a digital camera, and a camcorder that generally require a large capacity of power. As an example, multiple secondary batteries are connected to one another in series or in parallel, assembled as a hard pack having a predetermined shape in which a protection circuit is mounted, coupled to an electronic device, and used as a power supply.
A method of manufacturing the secondary battery stacks a negative plate coated with a negative active material, a separator, and a positive plate coated with a positive active material, couples one end of the stack structure to a winding axis having a pole shape, approximately rolls the stack structure in a cylindrical shape, and forms the electrode assembly. Thereafter, the electrode assembly is inserted into the cylindrical can. Then, the electrolyte is injected into the cylindrical can, and the cap assembly is coupled to a top portion of the cylindrical can, and thus a lithium ion battery having a cylindrical shape is completed.